package algotithm.acwing.test790;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * @author zhouyanxiang
 * @Date 2021-01-2021/1/6-11:10
 */
public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        double n = Double.parseDouble(reader.readLine());
        reader.close();
        search(n);
    }

    public static void search(double n) {
        final double m = 1e-8;
        double  l = 0, r = Math.abs(n);
        while (r - l > m) {
            double mid = l + (r - l) / 2;
            if (mid * mid * mid >= Math.abs(n)) {
                r = mid;
            } else {
                l = mid;
            }
        }
        if (n >= 0) {
            System.out.println(String.format("%.6f",l));
        } else {
            System.out.println("-" + String.format("%.6f",l));
        }
    }

}
